[1] Univ N Carolina, Sch Med, Div Gen Internal Med, Chapel Hill, NC 27599 USA
[2] Univ New Mexico, Coll Nursing, Albuquerque, NM 87131 USA
[3] Univ Calif San Francisco, Sch Med, San Francisco, CA USA
[4] Louisiana State Univ, Hlth Sci Ctr, Shreveport, LA 71105 USA
[5] Univ N Carolina, Cecil G Sheps Ctr Hlth Serv Res, Chapel Hill, NC 27599 USA